matrix wise tangent inverse (arctan)

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Given a matrix $X$, an expression for the matrix cosine and sine are given by $$ \textrm{cos}(X) = \frac{e^{iX} + e^{-iX}}{2}\\ \textrm{sin}(X) = \frac{e^{iX} - e^{-iX}}{2i} $$ I have been trying to find a convenient expression for the arctan with no luck. Is there any expression for the arctan? $$ \textrm{tan}^{-1}(X) = \text{?} $$